Sintered body for forming rare-earth permanent magnet and rotary electric machine having rare-earth permanent magnet

Abstract

This invention provides for a rotary electric machine that includes a rotor having a plurality of permanent magnets arranged in the circumferential direction, and in which the leakage of magnetic flux can be suppressed with a simple structure; and a rare-earth permanent magnet-forming sintered compact for forming rare-earth permanent magnets to be used in said rotary electric machine.

The invention claimed is: 
     
       1. A rotary electric machine comprising an annular stator and a rotor arranged on a rotational shaft arranged rotationally about a rotational axis in the stator to extend longitudinally through the stator with an air gap between the stator and the rotor, the rotor having at least one rare earth permanent magnet arranged with a lengthwise direction parallel with the rotational axis, said rare-earth magnet including a first surface extending in said lengthwise direction, a second surface distant in a widthwise direction from the first surface and extending in the lengthwise direction, and end surfaces located in the opposite end portions as seen in the lengthwise direction, at least one of the end surfaces being projected beyond a corresponding end surface of the stator toward a lengthwise outward direction;
 wherein: 
 said rare-earth permanent magnet comprises magnet material particles containing rare-earth materials sintered and formed into a shape having at least one of the end surfaces is formed into a first slanted surface which is slanted and extends from the lengthwise end portion of the first surface toward the lengthwise outward direction so that the magnet has a predetermined three dimensional shape having a length of the first surface shorter than the second surface; 
 said rare-earth permanent magnet includes divided regions at least including a lengthwise central region, and a first end region which extends from the at least one end surface to a portion apart from the end surface for a predetermined lengthwise distance; 
 in the central region, the magnet material particles in the central region are such that magnetization axes of the magnet material particles included in the central region are oriented in a parallel orientation wherein the magnetization axes of the magnet material particles are oriented substantially perpendicularly to the first surface which extends in the lengthwise direction; 
 said magnet material particles in the first end region are oriented in a portion adjacent to the at least one end surface toward the first surface in such a manner that the magnetization axes of the magnet material particles are oriented substantially along a slanted angle of the first slanted surface, but in a portion adjacent to the central region, the magnet material particles are oriented such that the magnetization axes of the magnet material particles are oriented substantially perpendicularly to the first surface, and in a portion between the at least one end surface and the central region, the magnetization axes of the magnet material particles are oriented such that an orientation angle of the magnetization axes of the magnet material particles are gradually changed from the end surface to the central region and converged toward the first surface. 
 
     
     
       2. The rotary electric machine in accordance with  claim 1 ; wherein said rare-earth permanent magnet is of a structure wherein the other of the end surfaces is projected beyond a corresponding end surface of the stator toward a lengthwise outward direction, in such a case, the other end surface is formed into a second slanted surface which is slanted and extends from a lengthwise end portion of the first surface toward the lengthwise outward direction so that the magnet has the predetermined three dimensional shape having the length of the first surface shorter than the second surface; said rare-earth permanent magnet including a second end region which extends from the other of the end surfaces to a portion apart from the other end surface for the predetermined lengthwise distance, and the magnet material particles in the second end region in a portion adjacent to the other end surface are oriented toward the first surface in such a manner that the magnetization axes of the magnet material particles are oriented substantially along the slanted angle of the first slanted surface, but in a portion between the other end surface and the central region, the magnetization axes of the magnet material particles are oriented such that the orientation angle of the magnetization axes of the magnet material particles are gradually changed from the end surface to the central region and converged toward the first surface. 
     
     
       3. The rotary electric machine in accordance with  claim 1 ; wherein said slanted angle θ 1  of the first slanted surface with respect to a line perpendicular to the first surface is in a range between 5° and 45°. 
     
     
       4. The rotary electric machine in accordance with  claim 2 ; wherein said slanted angle θ 2  of the second slanted surface with respect to a line perpendicular to the first surface is in a range between 5″ and 45°. 
     
     
       5. The rotary electric machine in accordance with  claim 1 ; wherein said slanted angle θ 1  of the first slanted surface with respect to a line perpendicular to the first surface is in a range between 5° and 15°. 
     
     
       6. The rotary electric machine in accordance with  claim 2 ; wherein said slanted angle θ 2  of the second slanted surface with respect to a line perpendicular to the first surface is in a range between 5° and 15°. 
     
     
       7. The rotary electric machine according to  claim 1 ; wherein said first end region is arranged such that it extends lengthwise outward direction beyond a corresponding lengthwise end surface of the rotor. 
     
     
       8. The rotary electric machine according to  claim 2 ; wherein said second end region is arranged such that it extends lengthwise outward direction beyond a corresponding lengthwise end surface of the stator. 
     
     
       9. The rotary electric machine according to  claim 1 ; wherein said first end region is defined to satisfy a relation 0.1≤a/L≤0.6, where 2 L is a lengthwise dimension of the second surface and is a lengthwise dimension of the first end region along the second surface. 
     
     
       10. The rotary electric machine according to  claim 2 ; wherein said second end region is defined such that a relation 0.1≤a/L≤0.6 is met, where 2 L is a lengthwise dimension of the second surface and is a lengthwise dimension of the second end region. 
     
     
       11. A sintered body for forming a rare-earth permanent magnet having a surface extending in a lengthwise direction and adapted to be assembled in a rotary electric machine with the surface arranged in parallel with a rotational axis of the rotor of the rotary electric machine;
 wherein; 
 said sintered body for forming a rare-earth permanent magnet includes magnet material particles containing rare-earth materials, sintered into a three dimensional body having a first surface extending in a lengthwise direction, a second surface distant in a widthwise direction from the first surface and extending in the lengthwise direction, and end surfaces located in the opposite end portions; 
 among the opposite end surfaces, at least one of the end surfaces is formed into a first slanted surface which is slanted and extends from a lengthwise end portion of the first surface toward the lengthwise outward direction so that the magnet has a predetermined three dimensional shape having a length of the first surface shorter than the second surface; 
 said sintered body for forming the rare-earth permanent magnet includes divided regions at least including a lengthwise central region, and a first end region which extends from the at least one end surface to a portion apart from the end surface for a predetermined lengthwise distance; 
 in the central region, magnet material particles in the central region are such that easy magnetization axes of the magnet material particles included in the central region are oriented in a parallel wherein the easy magnetization axes of the magnet material particles are oriented substantially perpendicularly to the first surface which extends in the lengthwise direction; 
 said magnet material particles in the first end region are oriented at least in a portion adjacent to the at least one end surface are oriented toward the first surface in such a manner that the easy magnetization axes of the magnet material particles are oriented substantially along a slanted angle of the first slanted surface, but in a portion adjacent to the central region, the magnet material particles are oriented such that the easy magnetization axes of the magnet material particles are oriented substantially perpendicularly to the first surface, and in a portion between the at least one end surface and the central region, the easy magnetization axes of the magnet material particles are oriented such that an orientation angle of the easy magnetization axes of the magnet material particles are gradually changed from the end surface to the central region and converged toward the first surface. 
 
     
     
       12. The sintered sintered body for forming a rare-earth permanent magnet in accordance with  claim 11 ; wherein the other end surface among the opposite lengthwise end surfaces is formed into a second slanted surface which is slanted and extends from a lengthwise end portion of the first surface toward the lengthwise outward direction so that the sintered body has the predetermined three dimensional shape having the length of the first surface shorter than the second surface; said sintered body further including a second end region which extends from the other of the end surfaces to a portion a part from the other end surface for a predetermined lengthwise distance, the magnet material particles in the second end region in a portion adjacent to the other end surface toward the first surface are oriented in such a manner that the easy magnetization axes of the magnet material particles are oriented substantially along the slanted angle of the first slanted surface, and in a portion between the other end surface and the central region, the easy magnetization axes of the magnet material particles are oriented such that the orientation angle of the easy magnetization axes of the magnet material particles are gradually changed from the end surface to the central region and converged toward the first surface. 
     
     
       13. The sintered body for forming the rare-earth permanent magnet in accordance with  claim 11 ; wherein the slanted angle θ 1  of the first slanted surface with respect to the first surface is in a range between 5° and 45°. 
     
     
       14. The sintered body for forming a rare-earth permanent magnet in accordance with  claim 12 ; wherein the slanted angle θ 2  of the second slanted surface with respect to the first surface is in the range between 5° and 45°. 
     
     
       15. The sintered body for forming a rare-earth permanent magnet in accordance with  claim 11 ; wherein said slanted angle θ 1  of the first slanted surface with respect to the first surface is in a range between 5° and 15°. 
     
     
       16. The sintered body for forming a rare-earth permanent magnet in accordance with  claim 12 ; wherein the slanted angle θ 2  of the second slanted surface with respect to the first surface is in the range between 5° and 15°. 
     
     
       17. The sintered body for forming a rare-earth permanent magnet according to  claim 11 ; wherein the first end region is defined to satisfy a relation 0.1≤a/L≤0.6, where 2 L is a lengthwise dimension of the second surface and is a lengthwise dimension of the first end region along the second surface. 
     
     
       18. The sintered body for forming a rare-earth permanent magnet according to  claim 12 ; wherein the second end region is defined to satisfy a relation 0.1≤a/L≤0.6, where 2 L is a lengthwise dimension of the second surface and is a lengthwise dimension of the first end region along the second surface.